With the development of display technology, liquid crystal display (LCD) and other planar display devices have advantages including high quality, power saving, thin body, wide application and etc. Accordingly, they are widely used in mobile phones, televisions, personal digital assistants, digital cameras, notebook computers, desktop computers and other consumer electronics products, and become the mainstream display devices.
Most of the current liquid crystal display devices are backlight-type liquid crystal display devices. The backlight-type liquid crystal display devices comprise a housing, a liquid crystal panel disposed in the housing, and a backlight module disposed in the housing. In general, a liquid crystal panel is composed of a color filter (CF) substrate, a thin film transistor array substrate (TFT Array Substrate), and a liquid crystal layer sandwiched between the CF substrate and the TFT substrate. The working principle of the liquid crystal panel is applying driving voltage to control rotation of liquid crystal molecules of the liquid crystal layer, for controlling the output of light and for refracting light from the backlight module to generate images. The assembling process of a liquid crystal display panel generally comprises array substrate (Array) processes (thin film, photolithography, etching and stripping processes), CF substrate processes, and cell processes (attaching the TFT substrate and the CF substrate).
After the liquid crystal display panel is manufactured, due to the limitation of fabrication processes, each liquid crystal display panel would have different degrees of brightness non-uniformity (grayscale mura) phenomenon. In the prior art, to compensate the grayscale mura of the liquid crystal display panel, a liquid crystal display panel photographed by a camera displays a screen in different grayscale. A grayscale compensation data is obtained according to the brightness difference of the display screen. The grayscale compensation data is stored in a flash memory. After a timing controller (Tcon IC) is turned on, a grayscale data to be displayed is compensated with the grayscale compensation data first, and then the compensated grayscale data is output for displaying a screen. As a result, the brightness uniformity of the liquid crystal display panel is improved.
However, in the prior art, when the grayscale compensation data is obtained, it is necessary to pair the liquid crystal display panel with the test backlight module on the test machine. The light source is provided to the liquid crystal display panel through the test backlight module so as to display images. The grayscale compensation data is then obtained through photographing the display screen of the liquid crystal display panel by the camera. If there is a significant brightness difference in the test backlight module itself due to the influence of longtime use and other reasons, the brightness difference in the screen photographed by the camera may not come from the liquid crystal display panel but come from the test backlight module. The grayscale compensation data obtained from this screen is not for the liquid crystal display panel itself, either, but for the common grayscale compensation data of both the liquid crystal display panel and the test backlight module. After the liquid crystal display panel is paired with the production backlight module without obvious brightness difference, the brightness difference of the liquid crystal display panel is still compensated with this grayscale compensation data. As a result, due to the wrong grayscale compensation data, new brightness difference would be induced.